(Philadelphia, PA) Smokers with a specific combination of two genetic variants
may be more likely to remain abstinent and less prone to relapse when trying
to quit smoking, a study by researchers from the Tobacco Use Research
Center of the University of Pennsylvania School of Medicine indicates.
This research – which will appear in the October issue of Health Psychology-
has important implications for the development of more effective treatment strategies
that are tailored to individual smokers’ needs.

“While previous research has examined the effects of genes related to
dopamine, a chemical in the brain associated with reinforcing the effects of
nicotine, this study provides the first evidence that genes that alter dopamine
function may influence smoking cessation and relapse during treatment,”
said lead author Caryn Lerman, Ph.D., Associate Director for
Cancer Control and Population Science at the Abramson Cancer Center
of the University of Pennsylvania and Professor in Penn’s School
of Medicine and the Annenberg Public Policy Center.

Dr. Lerman led a research team that examined 418 smokers enrolled in a randomized
placebo-controlled clinical trial of bupropion for smoking cessation. Participants
provided blood samples and received bupropion or placebo plus seven sessions
of behavioral group counseling. Smoking status, abstinence symptoms and side
effects were recorded weekly, and smoking status was verified at the end of
treatment and again at a six-month follow-up appointment.

Researchers found that participants with particular variants of the SLC6A3
dopamine transporter gene and the DRD2 dopamine receptor gene reported significantly
higher abstinences rates and a longer time before relapse than smokers carrying
other variants of these genes.

“This gene-gene interaction provides new evidence for the effects of
dopamine genes on prospective smoking cessation and underscores the importance
of not limiting genetic investigations of smoking behavior to single gene effects,”
said Lerman.

In previous research, the same variant of the dopamine transporter gene has
been associated with higher levels of dopamine in the brain and this may facilitate
smoking cessation. “Future smoking cessation studies should evaluate genetic
predisposition, as well as the influence of psychological and environmental
factors that may promote relapse,” stated Lerman.

This research will appear in Health Psychology in an article titled “Effects
of Dopamine Transporter and Receptor Polymorphisms on Smoking Cessation in a
Bupropion Clinical Trial.”

This research was funded by the National Cancer Institute and the National Institute
on Drug Abuse and was conducted by the University of Pennsylvania/Georgetown
University Transdisciplinary Tobacco Use Research Center.

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The Abramson Cancer Center of the University of
Pennsylvania was established in 1973 as a center of excellence in cancer research,
patient care, education and outreach. Today, the Abramson Cancer Center ranks
as one of the nation’s best in cancer care, according to US News and World
Report, and is one of the top five in National Cancer Institute (NCI) funding.
It is one of only 39 NCI-designated comprehensive cancer centers in the United
States. Home to one of the largest clinical and research programs in the world,
the Abramson Cancer Center of the University of Pennsylvania has 275 active
cancer researchers and 250 Penn physicians involved in cancer prevention, diagnosis
and treatment.

PENN Medicine is a $2.2 billion enterprise dedicated
to the related missions of medical education, biomedical research, and high-quality
patient care. PENN Medicine consists of the University of Pennsylvania School
of Medicine (founded in 1765 as the nation's first medical school) and the University
of Pennsylvania Health System (created in 1993 as the nation's first integrated
academic health system).

Penn's School of Medicine is ranked #2 in the nation for receipt
of NIH research funds; and ranked #4 in the nation in U.S. News & World Report's
most recent ranking of top research-oriented medical schools. Supporting 1,400
fulltime faculty and 700 students, the School of Medicine is recognized worldwide
for its superior education and training of the next generation of physician-scientists
and leaders of academic medicine.

Penn Health System consists of four hospitals (including its
flagship Hospital of the University of Pennsylvania, consistently rated one
of the nation's "Honor Roll" hospitals by U.S. News & World Report), a faculty
practice plan, a primary-care provider network, three multispecialty satellite
facilities, and home health care and hospice.